Cognition, Hearing and Audition

Cognition, Hearing and Audition Research Group

Within the Department of Cognitive Science, we have a number of researchers with interests in aspects of hearing, audition and cognition. This includes the relationship between cognitive processes and the way in which the human brain processes auditory information, as associated with hearing loss, hearing restoration and cognitive disorders.

The Department of Cognitive Science (including the researchers in the Cognition, Hearing and Audition Research Group) has recently relocated to the Australian Hearing Hub. The Australian Hearing Hub is a unique, world-class facility purpose-designed to facilitate collaborative research and teaching in hearing and related speech and language disorders. Our staff and students are uniquely placed to develop and build collaborations with other organisations and institutions also located in the Australian Hearing Hub, including: Australian Hearing, incorporating the National Acoustic Laboratories; implantation teams from Cochlear Limited and the Sydney Cochlear Implant Centre; as well as major not-for-profit organisations including The Shepherd Centre and the Royal Institute for Deaf and Blind Children.

Projects

Example Projects

This project has used electroencephalography (EEG) to measure a brain response, known as the acoustic change complex (ACC), to subtle changes within continuous sounds. The ACC is more reliable than the mismatch response and provides a more direct measure of auditory change detection. An equivalent study with magnetoencephalography (MEG) is now underway. Preliminary results indicate that the ACC can also be detected using MEG. The advantage of using MEG rather than EEG is that allows clearer differentiation of responses originating in the left and right hemispheres of the brain.

An assessment of auditory impairments in congenital amusia and dyslexia

Dyslexia, specific language impairment (SLI), and congenital amusia (CA) are all communication disorders associated with auditory processing impairment, yet there is little agreement on their distinctive and overlapping characteristics. As listening to music requires detailed sound processing, it has been claimed that musical interventions improve reading skills and that music syntactic processing is impaired among children with SLI. We aim to characterise and compare these three disorders using behavioural and electrophysiological measures to identify sources of convergence and divergence between music and language, critically evaluate music-based intervention for language impairments, and develop a framework for understanding auditory-based communication disorders.

Atypical neural responses to illusory auditory pitch in children with autism

Atypical auditory perception is a widely recognised but poorly understood feature of autism. In this research, we have measured the brain responses of 10 autistic children as they listened passively to dichotic pitch stimuli, in which an illusory tone is generated by sub-millisecond inter-aural timing differences in white noise. Relative to control stimuli that contain no inter-aural timing differences, dichotic pitch stimuli typically elicit an object related negativity (ORN) response, associated with the perceptual segregation of the tone and the carrier noise into distinct auditory objects. Autistic children failed to demonstrate an ORN, suggesting a failure of segregation; however, comparison with the ORNs of age-matched typically developing controls narrowly failed to attain significance. More striking, the autistic children demonstrated a significant differential response to the pitch stimulus, peaking at around 50 milliseconds. This was not present in the control group, nor has it been found in other groups tested using similar stimuli. This response may be a neural signature of atypical processing of pitch in at least some autistic individuals.

Auditory gap discrimination and stuttering

PAUL SOWMAN, ANDY ETCHELL

The control of speech relies heavily on accurately timed auditory feedback. A deficit in the auditory system’s ability to resolve auditory inputs with to the necessary level of temporal resolution has been posited as a possible cause for stuttering. This research aims to use MEG to determine the brains ability to discriminate highly temporally resolved stimuli in children who stutter and compare this ability to their fluent peers.

Auditory perceptual anchoring in children with dyslexia

This research has investigated auditory perceptual anchoring in dyslexia using a frequency discrimination task, in which two tones (between 1000 and 1500 Hz) are presented and participants are asked to judge whether the first or second presented tone is higher in pitch. In one ('standard') condition, one of the tones remained constant (1000 Hz) throughout the experiment. In the other ('no standard') condition, one tone was randomly presented from within a given range (1000 to 1400 Hz). Results from 24 children with dyslexia (poor with regular, irregular, or non-word reading; aged 6-13 years) and 19 children with age-appropriate reading showed that, relative to children with age-appropriate reading, dyslexic children performed more poorly overall and did not show the same degree of expected benefit in the standard condition. Interestingly, within the dyslexic group, however, one group showed poor thresholds in both the 'standard' and 'no standard' condition and another group showed good thresholds in the 'standard' condition and poor thresholds in the 'no standard' condition. Overall, frequency discrimination was related to phonological abilities.

Auditory processing and language impairment in children with autism using magnetoencephalography (MEG)

SHU YAU, JON BROCK

This research aims to clarify fundamental disturbances in perceptual and cognitive processes in autism spectrum disorders (ASD), looking at the relationship between auditory processing and the nature of language impairment in ASD, cortical responses (magnetic mismatch negativity) to basic speech and nonspeech sounds, and relating these to the degree of language impairment in children with ASD.

Auditory processing deficits in children with dyslexia and specific language impairment

GENEVIEVE MCARTHUR

This research aims to understand the causes of, and optimal treatments for, dyslexia and specific language impairment (SLI). In particular, I am investigating the role of auditory processing deficits in children with dyslexia and SLI. My previous research has shown that around 40% of children with dyslexia and SLI have a general auditory processing or speech processing deficit, and that these deficits can be improved with training, but that this has no direct impact on reading, spoken language, or spelling impairments in children older than 6 years.

Brain dynamics of timing in people who stutter

ANDY ETCHELL, PAUL SOWMAN

The production of fluent speech relies heavily on rhythmic structure and timing. Being able to accurately concatenate up to 6 syllables per second in order to maintain a fluent stream of speech represents a significant demand on the brain systems that support speech. In people who stutter the ability to maintain these fluent rhythms is compromised such that their speech is interrupted. We are using MEG to investigate the brain mechanisms that underlie the ability to entrain to rhythm and see how these might be affected in people who stutter.

Cognitive skills and compensatory strategies used by children with cochlear implants and children with dyslexia

Phonological skills and phonological representations are generally considered to be important prerequisites for reading development. Two groups of children, those who have profound hearing impairments and wear cochlear implants, and children with dyslexia, both have poor phonological representations and poor phonological skills. These conditions make development of basic reading skills more difficult for these populations of children and should be expected to have consequences also for later stages in reading development where whole words are generally recognised quickly and automatically. Previous research has reported that these children often experience reading problems even as adolescents and adults, which may have consequences for their everyday lives and careers. This research aims to uncover the cognitive skills and compensatory strategies necessary for these children to develop skilled reading. The cognitive skills investigated are working memory, lexical access, phonological skills, and association between phonological and visual information, and we also consider the effects of different types of practice (reading vs. spelling) on reading performance. Increased knowledge in this area will inform the provision of relevant and efficacious education and intervention programs.

Exploring the sound systems of Aboriginal languages and the implications for language learning

This research has involved a range of studies examining the sound system of Arandic languages, child-directed speech (where the sound system is simplified), and the nature of child speech. Adult data from 14 speakers has been collected using ultrasound imaging methods, and is currently being analysed. There is no funding available for analysis of pilot data of child and child-directed speech (1 3-year-old and 1 mother), nor for collecting more data. Both are critical for better understanding what the children in these communities speak at school, and how this impacts on learning and reading skills. This is all the more important given the reported high instance of otitis media and hearing loss in many remote communities throughout Australia.

Meditation and auditory attention: Effects on behavioural and neurophysiological measures

This project examines the effects of meditation on the brain. Previous research has shown that meditation leads to improved concentration and greater ability to cope with stress and anxiety. The study we are conducting examines what parts of the brain might be associated with these changes. We are specifically looking into auditory attention and its relationship with meditation.

MEG study of auditory change detection

FABRICE BARDY, SHU YAU, JON BROCK, BLAKE JOHNSON

Electroencephalography (EEG) and magnetoencephalography (MEG) studies of auditory perception in disorders such as autism, schizophrenia, language impairment and dyslexia typically focus on the mismatch negativity response. Participants hear a sequence of identical 'standard' sounds containing occasional 'deviant' sounds. The mismatch negativity is calculated by subtracting the brain response to standard sounds from responses to the deviant. Unfortunately, the mismatch response is not particularly reliable, so it is not suitable for measuring differences between individuals.

MEG study of oscillatory brain function in preschoolers

JON BROCK, YATIN MAHAJAN (UNIVERSITY OF WESTERN SYDNEY), WEI HE

This project investigates the brain function of preschoolers, and makes use of the one of the world’s first child magnetoencephalography (MEG) systems, which is housed in the Australian Hearing Hub. Using the child MEG, this project examines changes in brain responses to sounds in typically developing preschool children. Thirty-five children, aged 2-5 years, have been tested.

Neural signatures of auditory discrimination in adults

The mismatch negativity (MMN) is currently a de facto standard for objective measurement of auditory discrimination ability in adults and children. The current study investigated the properties of the MMN in comparsion to a lesser known electrophysiological measure, the acoustic change complex (ACC). Neuromagnetic responses were measured in four normal hearing adults. The results indicate that the ACC is superior to the MMN on a number of parameters: it is less variable, has a larger amplitude, a clearer waveform morphology, clearer hemispheric differences and is more sensitive to linguistic information. These results indicate that the ACC may be a useful neural marker of auditory discrimination in children and special populations.

Neural signatures of musical pitch imagery in adults

REBECCA GELDING, BLAKE JOHNSON, BILL THOMPSON

In this study we are developing an improved method for inducing and training mental imagery of musical pitch. We have developed an imagery task that has several advantages over previous imagery paradigms: it is extremely difficult to perform with non-imagery strategies, provides an objective behavioural outcome measure of imagery performance and induces high and stable levels of imagery. We have tested the task on six participants. We now plan to carry out a comprehensive behavioural experiment with the task, prior to measuring brain responses induced by the task. We also plan to develop a version that taps musical rhythm imagery.

Neural signatures of rhythm processing in children

Adults are able to unconsciously predict the onset of a rhythmic sound. We investigated whether children exhibit the same ability. Brain activity was recorded from 18 typically developing children (aged 3-10) while they listened to trains of isochrononous sounds (450ms inter-stimulus interval (ISI)) and non isochronous sounds (randomly varying between 300ms and 600ms with an average ISI of 450ms). The results indicate a greater increase in beta band power prior to stimulus onset in the isochronous relative to the non isochronous condition and support the conclusion that children are indeed able to unconsciously track rhythm.

Neural signatures of temporal processing in adults and pre-school children

JOANN TANG, BLAKE JOHNSON, JON BROCK, STEPHEN CRAIN, KATHERINE DEMUTH

This project investigates the role of different time scales in processing auditory/linguistic information in human auditory cortex. We measured magnetoencephalography (MEG) auditory cortical responses to amplitude-modulated sounds in 20 adults and 20 pre-school children. We found strong phase locked responses following the stimulus temporal modulations across a wide range of frequency (1-80Hz) in adults but not in children. Further investigation will be underway to look at these different time scales in processing natural speech.

Objective measurement of tinnitus and its remediation

This study examines the efficacy of a commercial technique (Neuromonics) for remediation of Tinnitus. Resting and evoked brain activity was recorded with magnetoencephalography (MEG) from 10 normal hearing controls and 15 tinnitus patients before and after three time points after the start of the intervention. Resting alpha band magnitude was significantly lower in the tinnitus patients prior to remediation, consistent with previous reports. Alpha magnitude progressively approached control magnitudes with time from the start of intervention. These results support the conclusion that the resting alpha provides an objective neural marker of tinnitus and its remediation.